Device housing and method for making the device housing

ABSTRACT

A method for making a device housing includes the steps of: providing a substrate; forming a base paint layer on the substrate by spraying; sensitizing a surface of the base paint layer; activating the surface of the base paint layer; providing a first water solution and a second water solution, the first water solution containing silver nitrate and ammonia water, the second water solution containing potassium sodium tartrate and sodium hydroxide; forming a silver layer on the sensitized and activated surface of the base paint layer by simultaneously spraying the first water solution and the second water solution on the sensitized and activated surface of the base paint layer; and forming a protective layer on the silver layer.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. Ser. No.13/593,621, filed Aug. 24, 2012, the contents of which are herebyincorporated by reference. The patent application Ser. No. 13/593,621 inturn claims the benefit of priority under 35 USC 119 from Chinese PatentApplication 201110359319.X, filed on Nov. 14, 2011.

BACKGROUND

1. Technical Field

The present disclosure relates to device housing and a method for makingthe device housing.

2. Description of Related Art

Housings of electronic devices, such as mobile phones, are commonlydecorated with decorative layers formed by surface treatments. Thesurface treatments may be anodizing, electrophoresis, and painting.However, the decorative layers formed by the mentioned surfacetreatments are not always aesthetically pleasing.

Therefore, there is room for improvement within the art.

BRIEF DESCRIPTION OF THE DRAWING

Many aspects of the disclosure can be better understood with referenceto the following FIGURE. The components in the FIGURE are notnecessarily drawn to scale, the emphasis instead being placed uponclearly illustrating the principles of the disclosure.

The FIGURE is a cross-sectional view of an exemplary embodiment of adevice housing.

DETAILED DESCRIPTION

Referring to the FIGURE, a device housing 100 according to an exemplaryembodiment is shown. The device housing 100 includes a substrate 10, abase paint layer 20 directly formed on the substrate 10. A sensitizationlayer 21 directly formed on the base pain layer 20, an activation layer23 directly formed on the sensitization layer 21, a silver layer 30directly formed on the activation layer 23, and a protective layer 40directly formed on the silver layer 30.

The substrate 10 may be made of metal or non-metal. The metal may bealuminum, aluminum alloy, magnesium, or magnesium alloy, for example.The non-metal may be plastic, for example.

The base paint layer 20 contains mainly acrylic acid epoxy resin.

The sensitization layer 21 is a thin gel layer containing hydroxidedi-tin chloride (Sn₂(OH)₃Cl). The Sn₂(OH)₃Cl has reducibility.

The activation layer 23 contains palladium (Pd) ions. The activationlayer 23 is evenly dispersed on the sensitization layer 21.

The protective layer 40 is a transparent or translucent resin layer andis for protecting the silver layer 30 from being scratched.

A method for making the device housing 100 may include the followingsteps.

The substrate 10 is provided and surface treated. The surface treatmentsfor the substrate 10 may be degreasing first and then polishing.

The base paint layer 20 is sprayed on the substrate 10. The paint orcoating used for forming the base paint layer 20 may contain mainlyacrylic acid epoxy resin. The spraying pressure of the paint or coatingfor the base paint layer 20 is about 1200 Pa. The spraying of the basepaint layer 20 lasts for about 2.4 seconds. During the spraying, thedistance between the substrate 10 and the spray gun (not shown) forspraying the base paint layer 20 is about 20 mm. The base paint layer 20smoothens the substrate 10.

The substrate 10 having the base paint layer 20 is baked in an oven (notshown) having an internal temperature of about 88° C. for about 30minutes.

The base paint layer 20 is sensitizing treated to form the sensitizationlayer 21. The sensitizing treatment is carried out by sprayingsensitizing water solution to the base paint layer 20. The sensitizingwater solution contains hydrochloric acid having a concentration ofabout 250 g/L to about 400 g/L, tin dichloride having a concentration ofabout 50 g/L to about 100 g/L, and potassium sodium tartrate having aconcentration of about 80 g/L to about 160 g/L. The components containedin the sensitizing water solution react to generate the Sn₂(OH)₃Cl gel.In the sensitizing water solution, the potassium sodium tartrate acts asa complexant to prevent the bivalent tin of the tin dichloride fromoxidizing to tetravalent tin.

The base paint layer 20 is activating treated to form the activationlayer 23. The activating treatment is carried out by dipping the basepaint layer 20 having the sensitization layer 21 in an activating watersolution for about 5 seconds to about 20 seconds. The activating watersolution contains hydrochloric acid having a concentration of about 20g/L to about 50 g/L, and palladium chloride having a concentration ofabout 0.1 g/L to about 0.5 g/L. The Pd ions contained in the activationlayer 23 act as a catalyst which accelerate the subsequent silver mirrorreaction.

The substrate 10 having the activation layer 23 is washed and then bakedin the oven (not shown) having an internal temperature of about 88° C.for about 30 minutes.

The silver layer 30 is formed on the activation layer 23. A first watersolution and a second water solution are provided. The first watersolution contains silver nitrate having a concentration of about 20 g/Lto about 40 g/L, and ammonia water having a concentration of about 30g/L to about 50 g/L. The second water solution contains potassium sodiumtartrate having a concentration of about 80 g/L to about 100 g/L, andsodium hydroxide having a concentration of about 10 g/L to about 20 g/L.The first water solution and the second water solution are heated fromabout 90° C. to about 110° C. and then simultaneously sprayed to theactivation layer 23. Then a silver mirror reaction is generated betweenthe components of the first and second water solutions, thereby formingthe silver layer 30 on the activation layer 23. The spraying process maylast for about 10 seconds to about 20 seconds. The spraying pressure ofthe first and second water solution is about 1000 Pa to about 1500 Pa.The potassium sodium tartrate of the second water solution acts as areductant during the silver mirror reaction.

The substrate 10 having the silver layer 30 is washed and then baked inan oven (not shown) having an internal temperature of about 60° C. forabout 30 minutes.

The protective layer 40 is sprayed on the silver layer 30 usingtransparent or translucent coating, such as acrylic acid epoxy resincoating. The spraying pressure of the coating for the protective layer40 is about 1200 Pa. The spraying of the protective layer 40 lasts forabout 2.4 seconds. During the spraying, the distance between thesubstrate 10 and the spray gun (not shown) for spraying the protectivelayer 40 is about 20 mm. The substrate 10 having the protective layer 40is then baked in the oven (not shown) having an internal temperature ofabout 88° C. for about 30 minutes to finish the device housing 100.

Specific examples of making the device housing 100 are described below.The forming and baking of the base paint layer 20 and the protectivelayer 40 in these specific examples may be substantially the same asdescribed above so it is not described here again The specific examplesmainly emphasize the specific concentrations of the water solutions anddifferent process parameters for the sensitizing treatment, theactivating treatment, and the spraying of the silver layer 30.

EXAMPLE 1

The substrate 10 was made of magnesium alloy.

Sensitizing treatment: the hydrochloric acid of the sensitizing watersolution had a concentration of 250 g/L, tin dichloride had aconcentration of 55 g/L, and potassium sodium tartrate had aconcentration of 80 g/L.

Activating treatment: in the activating water solution, the palladiumchloride had a concentration of 0.15 g/L, and the hydrochloric acid hada concentration of 20 g/L; the dipping process lasted for 5 seconds.

Spraying the silver layer 30: in the first water solution, the silvernitrate had a concentration of 25 g/L, and the ammonia water had aconcentration of 35 g/L; in the second water solution, the potassiumsodium tartrate had a concentration of 85 g/L, and the sodium hydroxidehad a concentration of 12 g/L; the first and the second water solutionwas heated to 100° C.; the spraying pressure of the first and the secondwater solution was 1100 Pa; the spraying process lasted for 15 seconds;the silver layer 30 was baked at an internal oven temperature of about60° C. for about 30 minutes.

EXAMPLE 2

The substrate 10 was made of aluminum alloy.

Sensitizing treatment: the hydrochloric acid of the sensitizing watersolution had a concentration of 300 g/L, tin dichloride had aconcentration of 80 g/L, and potassium sodium tartrate had aconcentration of 120 g/L.

Activating treatment: in the activated water solution, the palladiumchloride had a concentration of 0.30 g/L, and the hydrochloric acid hada concentration of 35 g/L; the dipping process lasted for 8 seconds.

Spraying the silver layer 30: in the first water solution, the silvernitrate had a concentration of 30 g/L, and the ammonia water had aconcentration of 40 g/L; in the second water solution, the potassiumsodium tartrate had a concentration of 95 g/L, and the sodium hydroxidehad a concentration of 10 g/L; the first and the second water solutionwas heated to 95° C.; the spraying pressure of the first and the secondwater solution was 1200 Pa; the spraying process lasted for 10 seconds;the silver layer 30 was baked at an internal oven temperature of about60° C. for about 30 minutes.

EXAMPLE 3

The substrate 10 was made of plastic.

Sensitizing treatment: the hydrochloric acid of the sensitizing watersolution had a concentration of 400 g/L, tin dichloride had aconcentration of 100 g/L, and potassium sodium tartrate had aconcentration of 160 g/L.

Activating treatment: in the activated water solution, the palladiumchloride had a concentration of 0.40 g/L, and the hydrochloric acid hada concentration of 50 g/L; the dipping process lasted for 10 seconds.

Spraying the silver layer 30: in the first water solution, the silvernitrate had a concentration of 35 g/L, and the ammonia water had aconcentration of 45 g/L; in the second water solution, the potassiumsodium tartrate had a concentration of 90 g/L, and the sodium hydroxidehad a concentration of 15 g/L; the first and the second water solutionwas heated to 105° C.; the spraying pressure of the first and the secondwater solution was 1400 Pa; the spraying process lasted for 20 seconds;the silver layer 30 was baked at an internal oven temperature of about60° C. for about 30 minutes.

The device housing 100 of the exemplary embodiments define a silverlayer 30 to provide the device housing 100 a silvery white and metallicappearance. Furthermore, the silver layer 30 can highly reflect light,which renders the device housing 100 high gloss.

It is believed that the exemplary embodiment and its advantages will beunderstood from the foregoing description, and it will be apparent thatvarious changes may be made thereto without departing from the spiritand scope of the disclosure or sacrificing all of its advantages, theexamples hereinbefore described merely being preferred or exemplaryembodiment of the disclosure.

What is claimed is:
 1. A method for making a device housing, comprising:providing a substrate; forming a base paint layer on the substrate byspraying; sensitizing a surface of the base paint layer; activating thesurface of the base paint layer; providing a first water solution and asecond water solution, the first water solution containing silvernitrate and ammonia water, the second water solution containingpotassium sodium tartrate and sodium hydroxide; forming a silver layeron the sensitized and activated surface of the base paint layer bysimultaneously spraying the first water solution and the second watersolution on the sensitized and activated surface of the base paintlayer; forming a protective layer on the silver layer.
 2. The method asclaimed in claim 1, wherein the silver nitrate has a concentration ofabout 20 g/L to about 40 g/L, the ammonia water has a concentration ofabout 30 g/L to about 50 g/L, the potassium sodium tartrate has aconcentration of about 80 g/L to about 100 g/L, and the sodium hydroxidehas a concentration of about 10 g/L to about 20 g/L.
 3. The method asclaimed in claim 2, wherein the first and second water solutions have atemperature of about 90° C. to about 110° C., and have a sprayingpressure of about 1000 Pa to about 1500 Pa.
 4. The method as claimed inclaim 1, wherein sensitizing the surface of the base paint layer iscarried out by spraying sensitizing water solution to the base paintlayer, the sensitizing water solution contains hydrochloric acid havinga concentration of about 250 g/L to about 400 g/L, tin dichloride havinga concentration of about 50 g/L to about 100 g/L, and potassium sodiumtartrate having a concentration of about 80 g/L to about 160 g/L.
 5. Themethod as claimed in claim 1, wherein activating the surface of the basepaint layer is carried out by dipping the base paint layer in anactivating water solution for about 5 seconds to about 20 seconds, theactivating water solution contains hydrochloric acid having aconcentration of about 20 g/L to about 50 g/L, and palladium chloridehaving a concentration of about 0.1 g/L to about 0.5 g/L.
 6. The methodas claimed in claim 1, wherein the base paint layer comprises acrylicacid epoxy resin.
 7. The method as claimed in claim 1, wherein theprotective layer is a paint layer comprising transparent or translucentresin formed by spraying.
 8. The method as claimed in claim 1, whereinthe substrate is made of metal or non-metal.
 9. The method as claimed inclaim 8, wherein the metal is aluminum, aluminum alloy, magnesium, ormagnesium alloy, the non-metal is plastic.